Q: Creating Array Key Name with Dynamic Array I am trying to get the example below to have key names for each dimension so it would look more like this:
Array
(
    [Mobile] => Array
        (
            [0] => Array
                (
                    [product_id] => 007
                    [product_name] => Blackberry R-900 Mobile
                    [product_price] => £450
                    [product_status] => 1
                    [product_category] => Mobile
                )

Instead of the example below,
I have included the class that I am using to create the array into a categorized array and the usage of it.
The function appendNode in array2arraytree is where the algorithm actually creates the new array for each category.
Thanks for any help. 
Example:
Array
(
    [0] => Array
        (
            [0] => Array
                (
                    [product_id] => 007
                    [product_name] => Blackberry R-900 Mobile
                    [product_price] => £450
                    [product_status] => 1
                    [product_category] => Mobile
                )

            [1] => Array
                (
                    [product_id] => 001
                    [product_name] => Wespro Multi-SIM & Touch-screen Mobile
                    [product_price] => £150
                    [product_status] => 1
                    [product_category] => Mobile
                )

            [2] => Array
                (
                    [product_id] => 004
                    [product_name] => Sigmatel MP4/MP3 + Camera Mobile
                    [product_price] => £150
                    [product_status] => 1
                    [product_category] => Mobile
                )

        )

    [1] => Array
        (
            [0] => Array
                (
                    [product_id] => 033
                    [product_name] => 8 GB Pendrive
                    [product_price] => £14.99
                    [product_status] => 0
                    [product_category] => Computers
                )

            [1] => Array
                (
                    [product_id] => 334
                    [product_name] => 250 GB Portable Hard Drive
                    [product_price] => £79.99
                    [product_status] => 1
                    [product_category] => Computers
                )

        )

    [2] => Array
        (
            [0] => Array
                (
                    [product_id] => 033
                    [product_name] => The White Tiger – Aravind Adiga
                    [product_price] => £29.99
                    [product_status] => 1
                    [product_category] => Books
                )

            [1] => Array
                (
                    [product_id] => 4501
                    [product_name] => The Final Reckoning - Sam Bourne
                    [product_price] => £19.99
                    [product_status] => 0
                    [product_category] => Books
                )

            [2] => Array
                (
                    [product_id] => 034
                    [product_name] => The Final Reckoning - Sam Bourne
                    [product_price] => £15.79
                    [product_status] => 0
                    [product_category] => Books
                )

        )

)

Usage:
<?php
require_once("array2arraytree.php");
$arrProducts=array(
    array(
        "product_id"            => "007",
        "product_name"          => "Blackberry R-900 Mobile",
        "product_price"         => "£450",
        "product_status"        =>"1",
        "product_category"      =>"Mobile"
    ),
    array(
        "product_id"            => "033",
        "product_name"          => "8 GB Pendrive",
        "product_price"         => "£14.99",
        "product_status"        => "0",
        "product_category"      => "Computers"
    ),
    array(
        "product_id"            => "033",
        "product_name"          => "The White Tiger – Aravind Adiga",
        "product_price"         => "£29.99",
        "product_status"        => "1",
        "product_category"      => "Books"
    ),
    array(
        "product_id"            => "4501",
        "product_name"          => "The Final Reckoning - Sam Bourne",
        "product_price"         => "£19.99",
        "product_status"        => "0",
        "product_category"      => "Books"
    ),
    array(
        "product_id"            => "001",
        "product_name"          => "Wespro Multi-SIM & Touch-screen Mobile",
        "product_price"         => "£150",
        "product_status"        => "1",
        "product_category"      => "Mobile"
    ),
    array(
        "product_id"            => "004",
        "product_name"          => "Sigmatel MP4/MP3 + Camera Mobile",
        "product_price"         => "£150",
        "product_status"        => "1",
        "product_category"      => "Mobile"
    ),
    array(
        "product_id"            => "034",
        "product_name"          => "The Final Reckoning - Sam Bourne",
        "product_price"         => "£15.79",
        "product_status"        => "0",
        "product_category"      => "Books"
    ),
    array(
        "product_id"            => "334",
        "product_name"          => "250 GB Portable Hard Drive",
        "product_price"         => "£79.99",
        "product_status"        => "1",
        "product_category"      => "Computers"
    )
);

$objTree=new Array2ArrayTree($arrProducts,"product_category");
$arrTree=$objTree->makeTree();
print("<pre>");
print_r($arrTree);
print("</pre>");
?>

Class Array2ArrayTree:
    

class Array2ArrayTree
{
    public $arrOriginal = array();
    public $arrDummy = array();
    public $strKey = "";

    public function __construct($arrData, $arrKey)
    {
        $this->arrOriginal = $arrData;
        $this->strKey = $arrKey;
        $this->arrDummy = array();
    }

    public function makeTree()
    {
        for ($i = 0; $i <= sizeof($this->arrOriginal) - 1; $i++) {
            $keyPosition = $this->searchKey($this->arrOriginal[$i][$this->strKey]);
            if ($keyPosition == -1) {
                $this->addNode($this->arrOriginal[$i]);
            } else {
                $this->appendNode($this->arrOriginal[$i], $keyPosition);
            }
        }
        return $this->arrDummy;
    }

    function searchKey($strCurrentValue)
    {
        for ($i = 0; $i <= sizeof($this->arrDummy) - 1; $i++) {
            if ($this->arrDummy[$i][0][$this->strKey] == $strCurrentValue) {
                return $i;
            }
        }
        return - 1;
    }

    function addNode($arrNode)
    {
        $this->arrDummy[sizeof($this->arrDummy)][0] = $arrNode;
    }

    function appendNode($arrNode, $keyPosition)
    {
        array_push($this->arrDummy[$keyPosition], $arrNode);
    }
}
?>


A: I think this would work - map the array to get the keys you want, then use array_filter to get only the items in that category:
//get the keys you want:
$keys = array_unique(array_map(function($item) { return $item['product_category']; }, $array));
$return = []; 
foreach($keys as $key) {
    //filter the array to the one's in the current category, and reindex them to 0:
    $return[$key] = array_values(array_filter($array, function($item) use ($key) { 
                        return $item['product_category'] == $key; 
                    }));
}


A: Should be even simpler:
public function makeTree()
{
    foreach($this->arrOriginal as $value) {
        $this->arrDummy[$value[$this->strKey]][] = $value;
    }
    return $this->arrDummy;
}

